The present invention relates to a process for the production of trans-4-hydroxy-L-proline microbially, especially by the cultivation of a microorganism of the genus Clonostachys, Gliocladium or Nectria.
The systematic name of trans-4-hydroxy-L-proline is (2S, 4R)-(-)-4-hydroxypyrrolidine-2-carboxylic acid, but this compound is, as is common in the art, herein referred to by its trivial name "trans-4-hydroxy-L-proline". It is a known compound which is used commercially for the synthesis of a number of compounds, notably carbapenem antibiotics, and it may be represented by the formula (I): ##STR1##
For example, starting from trans-4-hydroxy-L-proline it is possible to synthesize N-p-nitrobenzyloxycarbonyl-3-mercaptopyrrolidine or other synthetic intermediates [Heterocycles, 24, No. 5 (1986)], and this, in turn, can be used to prepare useful carbapenem antibiotics such as (5R,6S,8R)-6-(1-hydroxyethyl)-2-(pyrrolidin-3-ylthio)-2-carbapenem-3-carbo xylic acid (Japanese Patent Publication No. Sho 61-29357).
trans-4-Hydroxy-L-proline is one of the protein constituents of collagen and of elastin, both of which are proteins present in the connective tissue of animals. It is also present in the epidermal tissue of the earthworm in an amount which may be as much as 10 times the content of proline. Since it exists in such a large amount in collagen, it is commonly prepared from a gelatin hydrolysate by extraction and purification procedures. It has also been reported in certain higher plants, such as in the leaves of the sandalwood trees of the genus Santalum [Biochem. J. 117, 1013 (1970)]. However, the presence of free trans-4-hydroxy-L-proline has not previously been confirmed in microorganisms.
We have now found that microorganisms of the genera Clonostachys, Gliocladium and Nectria can produce trans-4-hydroxy-L-proline, which can be recovered from the culture medium in useful quantities.